<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>主页面与serviceWorker的通信</title>
</head>
<body>
  <div>
    <ul>
      <li>占位符</li>
    </ul>
    <input id="input" type="text">
    <button id="btn">发送信息</button>
  </div>
</body>
<script src="./msgApp.js"></script>
</html>